That's a great question! I've just filmed a video to answer it, but it will be a couple of days before it's up.
In the mean time,
The stitches you're supposed to knit look like V's. The stitches you're supposed to purl look like dashes. You can watch the video on doing ribbing (Basic Techniques/More page), which talks about how to recognize a purl and knit stitch.
KnittingHelp Queen Bee
"Don't ask yourself what the world needs. Ask yourself what makes you come alive and then go do that. Because what the world needs is people who have come alive." Howard Thurman